I agree with a VT, he's a pretty one at that too! As everyone has said, his tank is a bit on the small side. He would really like a larger tank for swimming, and it would be less work on you with water changes. If you went 1g or bigger, you would need to do water changes twice a week. In that tank, I would say 4 changes a week minimum. That's pretty darn stressful on owner and fish :) But yeah, welcome to the forum and congrats!

Not everybody can front up afford a larger tank. With regular cleaning (like 2x a week) the fish should be fine. Granted, betta are tropical fish and a heater should be priority. If you're concerned he might not have enough room now, remove the spongebob thing. But congrats on your fishie! He's beautiful!